A laparoscopic surgery is applied more and more widely. In order to avoid iatrogenic infection, the consumption of a disposable trocar used in the laparoscopic surgery is increasingly greater. The trend of simplifying the structure, reducing the cost, improving the performance on the basis of ensuring using performance has already become an improvement direction of the trocar.
In the laparoscopic surgery, when passing through the disposable trocar, a surgical instrument carries out an entry-exit reciprocating motion as well as a rotating motion. When a surgical instrument having a large diameter, such as a 10 mm or 12 mm surgical instrument, passes through a surgical instrument through hole of a 4 mm end sealing ring, the end sealing ring will generate a large surrounding force on the surgical instrument. In this case, the rotating motion of the surgical instrument inserted into the trocar may cause co-rotation of an end sealing piece and the instrument, thus causing loose between the end sealing piece and a near end of a sleeve of the trocar due to reverse movement so as to result in air leakage, or separating or disengaging the end sealing piece from the near end of the sleeve of the trocar so as to affect use of the trocar. Therefore, an improvement is needed.